Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
411 PM EST Fri Jan 31 2020

Valid 00Z Sat Feb 01 2020 - 00Z Tue Feb 04 2020


Days 1-3...

...Western U.S....
As much colder air associated with an amplifying trough supports
rapidly falling snow levels across much of the western U.S.,
strong low-to-mid level frontogenesis is forecast help produce
periods of moderate to heavy snow moving south and east through
the Intermountain West and Rockies through the weekend into early
next week.

An upper trough currently centered over the northeastern Pacific
is expected to shift east and amplify over the western U.S.,
bringing much colder air across the western U.S. through the
weekend.  Snow levels are forecast to plumet behind a strong cold
front dropping southeast from the Pacific Northwest on Saturday to
the Desert Southwest on Monday.

Strong low-to-mid level frontogenesis is expected to support
moderate to heavy snows developing and moving south and east over
the northern Intermountain West and Rockies late Saturday and
Sunday.  Areas most significantly impacted are expected to include
the north-central Idaho to southwestern Montana and northwestern
Wyoming mountains. 

By late Sunday and continuing in Monday, the greatest potential
for heavy snows will shift farther south and east - from southern
Montana to eastern Nevada.  A low level wave dropping southeast
across Wyoming is expected to enhance the potential for heavy
snows along the Big Horns, while extending the threat east into
the High Plains late Sunday into Monday.

The probability of significant icing (0.25-inch or greater) is
less than 10 percent.

Pereira